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Biomedical subjects

D J Alexander

Publications and source records attributed to D J Alexander.

At least 91 records · Page 5Linked to original sources
PubMed1993

Impaired mononuclear phagocyte function in patients with severe acute pancreatitis: evidence from studies of plasma clearance of trypsin and monocyte phagocytosis.

Activated proteases in plasma are complexed by alpha 2-macroglobulin. Although the complexes retain peptidase activity, they are usually eliminated promptly by mononuclear phagocytes. In severe acute pancreatitis, almost 30% of plasma alpha 2-macroglobulin becomes complexed, suggesting impaired clearance. In the present study, plasma [methyl-14C]trypsin clearance and monocyte phagocytosis were investigated. Attacks complicated by major organ-system failure, pancreatic pseudocyst, abscess, or necrosis were graded severe (median Ranson score 5.5). Plasma [methyl-14C]trypsin half-life was significantly increased in severe attacks (N = 7, median 21.1 min), compared to mild attacks (N = 14, median 15.4 min, P < 0.05) and healthy controls (N = 4, median 10.8 min, P < 0.02). Monocyte phagocytosis was significantly lower in severe attacks (N = 9, median 3.6%) compared to mild attacks (N = 20, median 20.8%, P < 0.01) and healthy controls (N = 8, median 26.9%, P < 0.01). Plasma [methyl-14C]trypsin half-life and monocyte phagocytosis were significantly inversely correlated (r = -0.51, P < 0.01). Impaired clearance of circulating trypsin in acute pancreatitis is potentially deleterious but may be reversed by stimulating mononuclear phagocytes.

Acute Disease↗
PubMed1993

Deduced amino acid sequences at the fusion protein cleavage site of Newcastle disease viruses showing variation in antigenicity and pathogenicity.

The amino acid sequence at the F2/F1 cleavage site of the F0 fusion protein of 17 strains of Newcastle disease virus (NDV) was deduced from sequencing a 32 nucleotide area of the genome by reverse transcription and polymerase chain reaction (PCR) techniques. With the addition of sequences at the same area previously published for 9 other viruses comparisons were made of a total of 26 NDV strains and isolates (11 of low virulence, 15 of high virulence or mesogenic) covering ten antigenic groups determined by reactions with monoclonal antibodies. All the virulent viruses and the mesogenic strain Komarov showed the amino acid sequence 112R/K-R-Q-K/R-R116 for the C-terminus of the F2 protein and phenylalanine (F) at the N-terminus of the F1 protein, residue 117. The mesogenic isolate of the antigenic variant NDV responsible for the recent panzootic in racing pigeons, often termed "pigeon paramyxovirus type 1", examined in this study had the sequence 112G-R-Q-K-R-F117. The deduced amino acid sequence in the corresponding region of all viruses of low virulence was 112G/E-K/R-Q-G/E-R-L117. The virulent virus, PMV-1/chicken/Ireland/34/90 (34/90), which had a close antigenic relationship to a group of avirulent viruses, three of which were examined in the present study as representatives of the monoclonal antibody group H, showed between 4-6 nucleotide differences from these viruses in the 32 nucleotide region studied. These resulted in differences in the deduced amino acid sequence at residue 112 E-->K, 115 E-->K and 117-->F, giving 34/90 a typical virulent virus motif at the cleavage site. Despite the extremely small portion of the genome studied there were several areas which appeared characteristic for 34/90 and the three group H viruses of low virulence, which suggests that they may have arisen from the same gene pool.

Amino Acid Sequence↗
PubMed1993

Deduced amino acid sequences at the haemagglutinin cleavage site of avian influenza A viruses of H5 and H7 subtypes.

The amino acid sequences at the haemagglutinin cleavage sites of 9 avian influenza A viruses of H5 subtype (5 high and 4 low pathogenicity for chickens) and 21 of H7 subtype (13 high and 8 low pathogenicity for chickens) were determined by direct RNA sequencing, PCR amplification sequencing or both. None of the viruses of low pathogenicity had multiple basic amino acids at the cleavage site. All highly pathogenic viruses had an insert of basic amino acids at the cleavage site, except A/chicken/Scotland/59 (H5N1) for which the multiple basic amino acids appeared as substitutions and not insertions. All highly pathogenic viruses examined conformed to the amino acid motif of R-X-R/K-R at the cleavage site which is considered to be essential for high pathogenicity in chickens, with the notable exception of highly pathogenic virus A/turkey/England/50-92/91 (H5N1) which had the sequence R-K-R-K-T-R adjacent to the cleavage site.

Amino Acid Sequence↗
PubMed1993

Fine bore silicone rubber and polyurethane catheters for the delivery of complete intravenous nutrition via a peripheral vein.

The aim of the study was to evaluate two fine bore catheters for the delivery of complete intravenous nutrition (IVN), of osmolality 1250 mosm/kg, via a peripheral vein. 50 patients were randomised to receive either a 23G silicone rubber catheter or 22G polyurethane catheter. The median duration of feeding was 9 days for silicone rubber catheters and 10 days for polyurethane catheters. Silicone rubber catheters developed complications significantly more frequently (44%) than polyurethane catheters (22%, p < 0.05). There was no significant difference in the median life span of the catheters removed because of complications, nor in the daily risk of thrombophlebitis. 92% of patients who were fed through a polyurethane catheter required only a single catheter for the duration of IVN. The peripheral venous route should be the first choice when the administration of IVN is considered for a period of less than 2 weeks.

Journal Article↗
PubMed1992

Characterisation of an antigenically unusual virus responsible for two outbreaks of Newcastle disease in the Republic of Ireland in 1990.

Antigenic characterisation of two highly virulent virus isolates from outbreaks of Newcastle disease on two closely connected farms in County Monaghan, Republic of Ireland, in 1990 showed the viruses to be indistinguishable but unlike other Newcastle disease viruses so far tested. However, they appeared to be antigenically closest to avirulent viruses isolated from waterfowl from several countries and from chickens in Northern Ireland in 1986. Despite the antigenic differences, chickens vaccinated with a live commercial Hitchner B1 vaccine were protected against intramuscular challenge with one of the virulent isolates.

Animals↗
PubMed1992

Influence of catheter type on occurrence of thrombophlebitis during peripheral intravenous nutrition.

To reduce the likelihood of thrombophlebitis during intravenous feeding through a peripheral vein, the osmolality of the solution is usually reduced by disproportionately raising the lipid content and lowering the carbohydrate, electrolyte, and aminoacid concentrations. The possibility that delivery system rather than feed is the main influence on the development of thrombophlebitis was examined in a randomised comparison of a fine-bore silicone catheter against a short 'Teflon' cannula. The nutrient solution given through a peripheral vein was a standard feed used for infusion into a central vein (osmolality 1250 mOsmol/kg, 13 g nitrogen, 200 g glucose [800 kcal], and lipid emulsion [1000 kcal]). 27 patients received the infusion through a fine-bore silicone rubber catheter (diameter 23 G, length 15 cm) and 23 through a teflon catheter (diameter 20 G, length 3.2 cm). The median duration of feeding was 5 days in each of the two groups. Thrombophlebitis developed in all patients in the teflon group but in only 2 (7%) of the silicone group. The first silicone catheter for a patient lasted a median of 128.5 h, compared with 40 h for the first teflon cannula (p less than 0.001). The results show that when a nutrient solution of osmolality 1250 mOsmol/kg is delivered through a peripheral vein with an ultrafine-bore silicone catheter, the risk of thrombophlebitis is low. For many patients intravenous feeding may thus be given through a peripheral instead of a central vein without compromising the nutritional adequacy of the feed.

Adolescent↗
PubMed1992

Treatment of acute pancreatitis caused by calculous obstruction of the pancreatic duct by ultrasound-guided percutaneous drainage.

In a small percentage of patients with acute pancreatitis, recurrent attacks of pain and hyperamylasaemia occur when feeding is commenced. Recurrences of this type may occur because the pancreas is still swollen and inflamed, and indicate the need for a longer period of "pancreatic rest" before food is introduced. Alternatively, they may reflect the presence of "mechanical" factors leading to the recurrent pancreatitis, such as a gallstone in the common bile duct, a pseudocyst of the pancreas, or pancreatic duct obstruction. Successful resolution of the pancreatitis may require treatment of underlying causative factors. A stone in the pancreatic duct (probably a gallstone) was found to be the cause of recurrent acute pancreatitis in an elderly patient with severe cardiovascular disease, who was unfit for surgery. Pancreatitis settled after percutaneous drainage of the pancreatic duct, the technique described.

Acute Disease↗
PubMed1992

Avian paramyxovirus serotype 1 (Newcastle disease virus)--infections in falcons.

From eight falcons and one pigeon which died from NDV over a period of 15 months in Dubai, United Arab Emirates, PMV-1 viruses were isolated on quail embryo cell cultures. The identification of all 9 strains were achieved with the haemagglutination inhibition test against polyclonal chicken PMV-1 antiserum, against mouse monoclonal antibodies as well as with the immunoperoxidase test. Intracerebral pathogenicity index and intravenous pathogenicity index tests were also carried out. Although the virus isolates in this study fell into two distinct groups, the overall clinical symptoms displayed by the falcons tailed to demonstrate any trends or specificity unique to a group. The isolate obtained from a pigeon was similar to the isolates from one group of the falcons and showed no identity with the pigeon variant virus.

Animals↗
PubMed1992

Characterisation of Newcastle disease viruses isolated in India.

Eleven Newcastle disease virus (NDV) isolates obtained from outbreaks of disease in chickens (9) and Japanese quail (2) in Tamil Nadu, India were characterised in pathogenicity tests, antigenically, using mouse monoclonal antibodies (MAbs), and other established tests devised to distinguish between different strains. All 11 isolates were shown to be highly virulent for chickens. In indirect immunoperoxidase tests used to assess the ability of a panel of 28 MAbs to bind to infected cell cultures, 10 of the isolates showed an identical reaction pattern, the other isolate (No. 4) failed to react with one MAb which bound to cells infected with the other isolates. Isolates 9 was unstable at pH 3 while the other 10 were stable. All other properties were shared by the 11 isolates.

Animals↗
PubMed1992

The immunology of virus infections.

In order to describe the complex virus-host relationship the authors review the viral mechanisms of infection and viral replication as well as the basic pattern of the immune responses. The delicate balance of the infection-immunity equation is complicated by the instability of both entities. The better understanding of these factors provides a rationale for the therapeutic counteraction of virus infections, reducing the likelihood of viral exposure becoming clinical viral infection.

Animals↗
PubMed1991

Evaluation of relationships between avian paramyxoviruses isolated from birds of the family Columbidae.

The prototype virus for the PMV-7 serotype of avian paramyxoviruses, PMV-7 dove Tennessee/4/75 (Tn 4) and five other isolates obtained from birds of the Columbidae family, which had been shown to be distinct from PMV-1 serotype, were tested for antigenic relationships between themselves and to other avian paramyxoviruses. By serological tests and analysis of structural polypeptides the viruses appeared to be distinct from other avian paramyxoviruses. One isolate appeared to be very closely related to Tn/4. Three other isolates showed only minor relationships to these two but were very closely related to each other. However, the sixth virus, pigeon Japan/Otaru/76, showed high levels of homology in haemagglutination inhibition tests and at least one line of identity in immunodoublediffusion tests with all five of the other isolates.

Animals↗
PubMed1991

A randomised study of the effects of osmolality and heparin with hydrocortisone on thrombophlebitis in peripheral intravenous nutrition.

Intravenous nutrition administered via the central route incurs both the risks of catheter insertion and catheter related sepsis. Peripheral intravenous nutrition avoids these risks but is associated with a high risk of thrombophlebitis. We undertook a study to look at the incidence of thrombophlebitis caused by the infusion of a) a 'ready to use' mixture (Vitrimix KV) with an osmolality of 1130 mOsmol/kg, b) Vitrimix KV plus heparin and hydrocortisone, and c) a feed, with an osmolality of 700 mOsmol/kg, with heparin and hydrocortisone, to investigate the effects of the addition of heparin and hydrocortisone and the effect of osmolality on the incidence of thrombophlebitis. The addition of heparin (500 u/l) and hydrocortisone (5 mg/l) to Feed A significantly reduced the daily risk of thrombophlebitis from 0.43 to 0.11 episodes per patient, p < 0.01. A reduction in the osmolality resulted in a further fall in the incidence of thrombophlebitis to 0.04 episodes per patient with a significant increase in the median life span of the cannula from 26 h to 86 h, p < 0.02. Our data show that a low incidence of thrombophlebitis can be achieved by the use of a low osmolality feed with heparin and hydrocortisone. It is recommended that peripheral intravenous nutrition be used in patients who require nutritional support for less than 10 days.

Journal Article↗